IW: typeof is not a function, missing ;
Merge pull request #18 from tangram-map/iwillig/minor-fixes

IW: typeof is not a function, missing ;
only iterate over active modes when rendering
Merge branch 'master' into async

Conflicts:
	dist/tangram-worker.min.js
	dist/tangram.debug.js
	dist/tangram.min.js
	src/scene.js
remove unused URL-based shader code
Revert "only iterate over active modes when rendering" - re-introduces flicker when rebuilding/switching modes

This reverts commit f885d690a8c49b4b2fc894d12be3a8bf8951cbf7.

Conflicts:
	dist/tangram-worker.min.js
	dist/tangram.debug.js
	dist/tangram.min.js
defer replacing GL programs until they finish compiling